New Jersey Gov. Chris Christie was in New Hampshire on Wednesday, warning Republicans that a failure to unite behind Donald Trump will hurt Sen. Kelly Ayotte's re-election chances.

Speaking at a state Republican Party "unity breakfast" in Bedford, Christie offered a harsh assessment of Republicans who don't fully support their party's presidential nominee.

"It's either going to be President Trump or President Clinton," Christie said. "Forget about Gary Johnson and Bill Weld, they're not going anywhere. You know it, I know it."

Christie, who dropped out of the Republican presidential race in February after a disappointing sixth place finish in the New Hampshire primary, became one of the first major elected officials to get behind Trump. He told Granite State Republicans why they need to do the same.

"If you are a Republican and you are not working for Donald Trump for the next 55 days, you are working for Hillary Clinton," he said.

It is a message that has resonated with even some of the once staunchest Trump opponents, like former New Hampshire Gov. John Sununu who said earlier this year that Trump had a history of failure and was a perpetual loser.

"I think Kelly Ann Conway is explaining to him that demeanor and style in the last 6 to 8 weeks of the campaign is critical," Sununu said. "I think he's being able to display his capacity to do that. I think it's made a big difference."

Christie, a close and trusted adviser to Trump, is also credited in part for Trump's recent uptick in the polls and as Christy is modeling, discipline to message.

When asked how serious he considered Hillary Clinton's medical issues and what impact he thought they would have on the race, Christie said he was not sure.